The objectives are to: 1. reduce rates of nosocomial infections; 2. define the magnitude of the problem of nosocomial infections in a representative sample of acute care hospitals using a standardized, prospective data collection system; 3. identify both modifiable and non-modifiable risk factors for nosocomial infection; 4. execute a controlled intervention trial based upon modifiable risk factors identified in the study to determine to what extent nosocomial infections are preventable; 5. measure the effectiveness (practicality, compliance, outcome improvement) of specific interventions in reducing nosocomial infections. METHOD: Standardized prospective surveillance will be established at all 14 nongovernment hospitals using inplace personnel to allow for collection of baseline data, study of nosocomial determinants and the identification of problem areas. After this intervention trials will be undertaken and evaluated using the same surveillance system. Comparisons between similar hospitals will be made to control for secular trends.